Breaker refused to trip

[Homeownerinburb]

Was installing a receptacle today in a bathroom, using the power to an abandoned wall heater. Went to panel to look for a breaker marked "wall heater" but found none. Tried to trip breaker by holding hot to metal box (metal conduit) and only got a heavy buzz in the wire as I insisted that the breaker should trip.

It is a relatively modern panel that dates to the 70's (to judge from the kitchen that was added at the same time).

Should I propose the client or the general who hired me that all the breakers be replaced?

 

[Bgard]

Try shorting it to nuetral, you probably don't have a good path to ground through the conduit, loose locknuts and setscrews

 

[Sponsor]

 

[Reach4]

Maybe they used a single pole breaker instead of a 2-pole.

 

[Homeownerinburb]

Try shorting it to nuetral, you probably don't have a good path to ground through the conduit, loose locknuts and setscrews

I probably won't get another chance.

 

[Homeownerinburb]

Maybe they used a single pole breaker instead of a 2-pole.

It was indeed a single breaker, but it being a 120v circuit, that is what I would expect.

 

[Homeownerinburb]

Try shorting it to nuetral, you probably don't have a good path to ground through the conduit, loose locknuts and setscrews

I doubt that I'll get another chance. There was a mighty moaning sound in the cable as I held the hot to the box...

 

[Stuff]

As this is not a homeowner DIY it would be better for them to pull in an electrician.

BTW: Finding a breaker by intentionally creating a short is not the safe way to do it. People get fired for that sort of thing. (When in school I got detention for showing someone that trick.)

 

[Jadnashua]

As was said...the box may not have been grounded well after nearly 50-years. Things would likely get warm, but not necessarily to trip the breaker.

 

[DonL]

As this is not a homeowner DIY it would be better for them to pull in an electrician.

BTW: Finding a breaker by intentionally creating a short is not the safe way to do it. People get fired for that sort of thing. (When in school I got detention for showing someone that trick.)

I agree.

And telling the owner that all of his breakers are bad, Because of a failed experiment is not right.

 

[WorthFlorida]

You as a hired hand or contractor and found a potential dangerous situation, you recommend that a licensed electrician be called. It's all in the liability. Should a fire occur or someone be shocked and injured, it can come back on you.

 

[Homeownerinburb]

As was said...the box may not have been grounded well after nearly 50-years. Things would likely get warm, but not necessarily to trip the breaker.

Yeah, the path back to the panel is likely compromised. Nothing to do about it assuming the owner does not want to rewire with a ground wire.

 

[Homeownerinburb]

You as a hired hand or contractor and found a potential dangerous situation, you recommend that a licensed electrician be called. It's all in the liability. Should a fire occur or someone be shocked and injured, it can come back on you.

What solution is there short of a full rewire including a ground?

 

[Homeownerinburb]

I agree.

And telling the owner that all of his breakers are bad, Because of a failed experiment is not right.

I agree now, it is likely not the breaker's fault. Very unlikely, in fact.

Any solution beyond a full rewire?

 

[Homeownerinburb]

As this is not a homeowner DIY it would be better for them to pull in an electrician.

BTW: Finding a breaker by intentionally creating a short is not the safe way to do it. People get fired for that sort of thing. (When in school I got detention for showing someone that trick.)

Yeah, and all it proved is that the path to ground is compromised by age.

 

[Jadnashua]

In the house where I grew up...BX, where the cable sheath was used as the grounding (no ground tape or wire). Over the years, if you measured from the metal box to the neutral, there was significant resistance, where it should be very close to zero ohms. To provide some protection without rewiring the whole house, I replaced the aging 2-prong receptacles with GFCI ones and grounded devices...which does meet code, although rewiring would have been better - it just wasn't in the scope. Trying to trip a breaker with shorting the leads will often take a chunk out of the point where you make the connection, or a chunk out of say a screwdriver...a circuit breaker is typically designed to only trip when the current in the short term, significantly exceeds the setting. On a constant load, it tends to trip over time, sometimes minutes when close, verses immediately, too. A fuse (unless a slow-blow) is different...almost immediate response.

 

[Bgard]

I should have said that shorting the wire to find the breaker was not a good idea sorry for that. a volt meter and an assistant flipping breakers or one of the electronic breaker finders would have been a better choice. the buzzing and moaning that you heard was the wiring and bad path to ground trying to obtain enough current to trip the breaker every bad connection in the ground path was vibrating at 60Hz and creating heat, there just was not enough resistance to provide it, (think 1500 watt toaster oven) each bad connection could have been heating like that. back in the days when that house was built not much thought went into grounding and the safety issues involved with it the only thing that needed to be grounded was the service panel and sometimes that was not done properly either. now the one of the biggest chapters in the NEC deals with bonding and grounding. if the house is completely done in conduit it would not be that hard to add an equipment grounding conductor in the conduit provided there are no hidden boxes that are not accessible. but it also depends on the condition of the rest of the wiring if it should just be completely rewired. I would not advise to put a receptacle in a bathroom with out a good ground even with a GFCI.

 

[Homeownerinburb]

if the house is completely done in conduit it would not be that hard to add an equipment grounding conductor in the conduit provided there are no hidden boxes that are not accessible. but it also depends on the condition of the rest of the wiring if it should just be completely rewired. .

Really? Fishing one more conductor into a conduit that has already got wire in it?

 

[Jadnashua]

The safety ground is there to provide a path to trip the breaker...it can add a level of safety, but as you found, there can easily be more than enough power leaking to ground to kill you even with a (poor) ground. Adding a GFCI is significantly safer than a grounded outlet by itself, and is a good compromise if you can't rewire. The level at which they are supposed to trip is 0.005A (5ma). Your failed test I'm sure had WAY more current flowing to ground than that...a GFCI would have tripped nearly instantly if you shorted the hot to ground. Any power that doesn't return to the source via the neutral means some of it is going where it is not intended...when that happens, the GFCI is designed to trip. A fixture ground is not required.

 

[Homeownerinburb]

Adding a GFCI is significantly safer than a grounded outlet by itself, and is a good compromise if you can't rewire. .

Yes. But at $13 plus 10% tax plus the cost of the labor to install the dratted things I doubt very much that the homeowner would go for it. Next time I am over there I'll certainly check to assure that they are present in the kitchen, I know that they are present in the other bathroom.